Wipes are well known commercial, consumer, and industrial products relied upon to assist in the removal of contaminants from surfaces. They are available in a wide variety of materials fashioned into relatively thin sheets. The earliest wipes were probably woven rags and these were replaced to some degree by thin sheet paper products. Unfortunately, rags and cellulosic paper products tend to shed fiber particles, and to tear, so that they can not be used to decontaminate surfaces to the low particulate levels required by many modern-day manufacturing processes.
Improved wipes followed the development of processes to produce filaments from synthetic polymeric materials such as the "meltblowing" process as described in U.S. Pat. No. 3,978,185 to Bunting et al. dated Aug. 31, 1976. This led to the substitution of such synthetic filaments for the cellulosic filaments by compressing and bonding the filaments into sheets, for example as given in U.S. Pat. No. 4,307,143 to Meitner, dated Dec. 22, 1981. Although these products had improved strength, and a reduced tendency to shed filaments, they were still relatively weak. Since the fibers were bonded and permanently compressed, they had a diminished interstitial volumes and therefor diminished abilities to absorb liquids. Modest absorption improvements resulted from creating patterned indentations in the sheet of polymer filaments as exemplified in U.S. Pat. No. D0,409,389 to May et. al., dated May 11, 1999.
The foregoing wipes all suffered from an inability to remove substantial amounts of solids contaminants because they could do so only by the attachment of the contaminant solids to the surface of the wipe, since the act of compressing and bonding of the filaments tended to create a fiber web which restricted the passage of solids contaminants into the interior of the wipe. Also, since these wipe products were in the form of thin two dimensional sheets, they had very little interior volume. Furthermore, since the filaments of the wipes were in a restrained and bonded state, particles which did find their way into the interstices of the fiber webs were not readily trapped could pass back out again, particularly if the wipes were used moistened or otherwise wetted with a carrier or solvent liquid.
Many laminate fabric species have been proposed during the last several decades in which sheets of meltblown filaments are compressed and bonded to external layers of substantially continuous non-woven "spunbonded" filaments. A recent example is given in U.S. Pat. No. 5,804,512 to Lickfield et. al. dated Sep. 8, 1998. These have increased strength, but the meltblown filaments are bonded, compressed, and restricted, and therefore have a limited ability to capture particles irreversibly and to absorb liquids. Also, these laminates tend to be stiff and therefore do not have the flexibility or "drape" required for a wipe to conform readily to the surface being decontaminated. Reduced conformation results in a corresponding reduction in wiping efficiency with an increased possibility that some sections of the surface being cleaned would be bypassed under the conditions which would reasonably occur in manufacturing operations.
The liquid absorptive capacities of the wipes described above could be enhanced by increasing their thickness. However, this would result in unacceptably high levels of stiffness.
Recent advances in manufacturing and processing technologies, and environmental concerns, have created a demand for more stringent levels of cleanliness. This has produced a corresponding need for economical wipe products that can provide increased capacities to remove contaminant solids, and to absorb cleaning liquids, coincident with low wipe fiber shedding, high wipe strength, and minimum wipe stiffness.